Syriac is thought to have appeared in the Middle East from the 1st Century and boasts a large Christian literature. It declined as a spoken language with the arrival of Islam and Arabic and today is only used in churches.
Thought to have appeared? Syriac is just the late form of Aramaic, the dominant language of the Middle East for close to a millennium, though written in a distinctive alphabet (two really) and it hardly just "appeared". It was written in everything from cuneiform to square letter Hebrew to the various varieties of Syriac scripts, and even occasionally in Arabic.
Nor is it only used in churches today: its Western form is spoken in four villages north of Damascus, and its Eastern form among the Assyrian communities of Iraq and Turkey. Syriac was once one of the world's great literary languages, and isn't quite dead yet. I have only the slightest smattering (alphabet, basic verb) but the Reuters reporter could have done better than this.
Now, go to the Cambridge University website on the same purported discovery. Here's a nuanced account quoting the academic making the claim with all the nuances intact, and with an illustration, which I reproduce above, and which seems to include the mark in question. (I make no judgment on his claims, which I'm not qualified to address, but at least the Cambridge site doesn't misstate facts.)
Really, what's so hard about that?